Apparatus for comminuting metals



.May 3, 1932. H. M. WILLIAMS ET AL 1,856,679

APPARATUS FOR COMMINUTING METALS Filed July 22, 1925 2 Sheets-Sheet 1Ill-mm 4| x 40 J I 4 l I l I 5 I WI um ZQL I Wm M- May 3, 1932. H. M.WILLIAMS ET AL 1,856,679

APPARATUS FOR COMMINUTING' METALS 2 Sheets-Sheet 2 Filed July 22, 1925Patented May 3, 1932 UNITED STATES PATENT OFFICE ABBY M.,WILLIAMS ANDVICTOR W. IBIHLMAN, OF DAYTON, OHIO, ASSIGNORS TO GENERAL'MOTORSRESEARCH CORPORATION, A CORPORATION OF DELAWARE APPARATUS FORCOIIIIMTNUTING METALS Application and July 22,

This invention relates to the comminuting of metals of relatively highmelting point, by atomizing them while in a molten condition, by astream of aeriform fluid under pressure.

I It hashitherto been proposed to atomize metals of relatively lowmelting point by melting them, letting the molten metahflow through anozzle and forcing a stream of air or steam into contact with the streamof molten metal. This process has been commercially practiced with lead,tin and other metals of relatively'low melting point. So far as I amaware, metals of high melting point,such as copper, nickel and the like,have never been commercially produced by this method.

It is an object of this invention to produce metallic powders of copper,or other'highmelting-point metals, by atomization.

The invention consists in the method-of atomizing high-melting-pointmetals, and in an apparatus for carrying out this method, as more fullydescribed hereinafter, illustrated in the accompanying drawings, anddefined in the appended claims.

In the drawings, in which like reference characters indicate. like partsthroughout the several views:

Fig. 1 is an elevation, partly in section, of an apparatus adapted topractice the process of this invention;

Fig: 2 isca sectionthrough a fragment of a furnace, crucible andatomizin'g nozzle, forming part of the invention; Fig. 3 is a section ofa fragment taken on the line 3-3 of Fig. 2, looking upward towa'd thebottom of the furnace and crucible; an

Fig. 4 is a view similar to Fig. 3. showing a modification in therelation of the inlet pipes to the'atomizing nozzles.

In Fig. 1, 10 indicates afurnace which may be of the combustion type,fed bycombustible gas through a pipe 11. A removable cover 12 normallycloses the upper end of said furnace, this cover may have a hole in it(not shown) for receiving a funnel by means of v which to guide moltenmetal into a crucible disposed in the interior thereof, as will beexplained presently. The furnace 10 has an 1925i Serial No. 45,284.

expansion space in a large pipe 13 beneath it. Pipe "13 is closed at itsupper end excepting that it has an opening registering with the openingin the furnace. The pipe 13, as shown in Fig. 1, curves to one side at14, and enters the lower portion of a large collection chamber lo'havingan inclined bottom 16, a top 17 which is open to the atmosphere,preferably through a fine-meshed fabric to pre-' vent metallic dustleaving the chamber 15 through the top. At the lower end of the inclinedpart 16, there is a door 18, through which copper or other metallicpowder, produced by the atomizing process to be described, may beremoved.

The furnace 10 may be built up of fire brick 19, or other refractorymaterial, within a shell of metal 20, and may be supplied withcombustible gas through pipe 11 at any suitable point, preferably justabove the ledge 19a, which may be formed of fire clay, or the like. Theledge of fire clay (19a is of annular form, the opening in it beinglined with a collar21 haying, an internal flange 22. The

opening within the flange 22 of said collar 21 is occupied by a bottommember 23, having a flange 24, resting upon the flange 22. Said bottommember 23 has a central hole 25 and one or more smaller holes 26,arranged around it. The collary2l and the bottom member 23 may be madeof cast iron, or preferably of some suitable high-heat-resistingmaterial, such as nichrome.

' Resting within the furnace 10 is a crucible 27 made of any of theusual materials adapted for the purpose, such as graphite. In the formshown in Fig. 2, the crucible 27 has an extension 28 of the samematerial, which is screw-threaded'into the bottom of the crucible, as at29, or may also be integral with it.

The extension 28 tapers downward and the lower end rests upon the bottomplate 23,. said extension having an opening in itslower end registering.with the opening 25. Into the lower end of extension 28, there issecured,

as. bykzrewthreads 30, a graphite nozzle 31 which has atapering lowerend protruding some distance below the extension 28, and an upper endextending some distance up into said extension. 1ne lower tapering endof the nozzle is pierced to receive a tube 32 made up of anysuitablematerial, as quartz or lavite, said tube being suitably securedin place. Above the quartz tube the graphite nozzle is counterbored asat 33, the upper end of the counterbore being closed by a cap 34, alsoof graphite. The walls of the graphite nozzle 31 are perforated as at35, to form passages for the entrance of molten metal from the crucibleinto the nozzle. of the presence of passages 35 the nozzle acts as astrainer to prevent the entrance into the nozzle of dross, slag, orother coarse material, which might act to clog the quartz tube 32.

The lower end of nozzle 31 protrudes some little distance below thelower side of the furnace, through the opening 25 in the bottom plate23. This end of the nozzle is encased by a shell 36. of heat-resistantmetal, to mechanically strengthen the graphite and pre vent burning.urroundihg the protruding end of the nozzle, is an annular nozzle forreceiving aeriform fluid under pressure, such as air, and discharging itin a converging stream, annular in cross-section, around the exit of thequartz tube 32. This annular nozzle will be termed, for convenience, anair nozzle. The main part of the air nozzle is indicated in Fig. 2 bythe numeral 37. The inner part of it comprises a shell 38 whichconforms, interiorly, substantially to the shell 36, but is spacedslightly therefrom in order that there may be no binding because ofwarping orexpansion due to heat. The said members 36, 37 and 38, shouldbe of highheat-resisting metal, and we have found that an alloy knowncommercially as Resistal, is well-suitedfor the purpose. Tapped into themember 37 of. the annular air nozzle, are pipes 39 leading from -asource (not shown) of air, or other suitable gaseous material, underpressure. The air nozzle may be secured. in place by any suitable means,iron bolts 40, as shown in Fig. 2, answer the purpose very well;although they may have to be replaced occasionally, owing to the de-'structive effect of heat to which they are subjected.

Surrounding the air nozzle and secured to the bottom plate 23, by saidbolts 40 and nuts 41, is a casing 42 made of sheet metal of suitablehigh-heat-resisting material, which mav be Besistal, or a metal knowncommercially as Ascoloy. Pipes 39 penetrate the wall of the casing 42and fit snugly therein. When the casing 42 is in place, it is in com--munication with the interior of the furnace within the furnace 10,products ofcombus tion will enter the chamber within the casing some ofthe products of combustion may pass Because fluid to issue from theannular orifice 44 in v a whirling state. In Fig. 4the air-conductingpipes 39a are shown disposed tangentially to effect increased agitationof the stream of molten metal where the air acts upon it.

In the practice of this method, copper or other relativelyhigh-melting-point metal is brought to a state of fusion in any suitableway. The furnace 10 is preheated to a high degree of heat by startingcombustion therein well in advance of the time of filling the crucible27 with the molten metal, so that the crucible is heated to a hightemperature and products of combustion circulating around the nozzleportions exteriorly of the furnace, said nozzle portions are alsopreheated to a relatively high temperature, say, from 1600 to 2000degrees Fahrenheit, more or less. When crucible and nozzles have beenbrought to the required temperature, the molten metal heated in anotherfurnace is conducted to the heated crucible 27. From said heatedcrucible, the molten metal flows through the small passages 35 into theinterior of the nozzle 31 and thence passes, free from dross or slag,into and through the quartz tube 32. While the molten metal is issuingfrom the quartz tube 32, the atomizing fluid is forced by pipes 39 intothe annular nozzle and out through the annular opening 4.4.beyond whichthe end of the quartz tube 32 protrudes slightly. The atomizing fluidtakes an inverse conoidal form, surrounding the stream of molten metal,which falls substantially into the'apex of the cone. This stream has anentraining action tending to withdraw molten metal from the crucible.The impact of the atomizing fluid and the sudden expansion of it, as itloses its force in the large expansion space afforded by the pipe 13,

breaks up the stream of metal into fine particles, which fall down thepipe and progress toward the door 18. The powder of copper and othermetals thus produced. mav be swept from the walls of the pipe 13, andthe chamber 15, and collected adjacent the door 18. from which it may beremoved.

It is found in the treatment of c per, that a large proportion of thepowder, approximately 75%, is of a size to pass through H 2OO -meshsieve, and that the powder of this 42, circulate around the nozzles, andthat.

fineness is pure copper, substantially free from oxide,"while thecoarser partlcles are found to be oxidized, more or less, and not usablewhere pure copper powders are needed, as in the manufacture of bushings,brushes. and the like.

While the form of embodiment of the invention as herein disclosed.constitutes a preferred form. it is to be understood that other formsmight be adopted, all coming within the vscope of the claims whichfollow.

What is claimed is as follows:

1. Apparatus for producing metallic powders of relativelyhigh-meltingpoint metals comprising. in combination, a furnace, acrucible in which the metal is melted, a nozzle connected with thecrucible and extending outside the furnace, means for directing the gaeous products of combustion from said furnace around the discharge endof the nozzlc to maintain the nozzle at a relatively high temperatureand means for subjecting the metal issuing from the nozzle to a whirlingstream of aeriform fluid under pressure and causing the products ofcombustion to flow around the part of said nozzle outside the furnace.

2. Apparatus for producing metallic powders of relativelyhigh-melting-point metals comprising. in combination, a furnace, acrucible in which the metal is melted. a nozzle connected with thecrucible and extending outside the furnacemeans for directing thegaseous products of combustion from said furnace around the dischargeend of the nozzlc to maintain the nozzle at a relatively hightemperature and means for subjecting the metal issuing from the nozzleto a hollow stream of aeriform fluid under pressure surrounding saidnozzle and causing the products of combustion to flow around the part ofsaid nozzle outside the furnace.

3. The combination of a furnace having an opening. a crucible disposedwithin the furnace. a nozzle connected to the crucible extending throughsaid opening, said nozzle having perforations adapted to function as astrainer of the metal entering the nozzle, and means for atomizing themetal issuing from the nozzle by a stream of aeriform fluid underpressure.

4. The combination of a. furnace having a bottom plate provided with anorifice, a crucible disposed within said -furnace, a nozzle connected tothe crucible and extending through the orifice in sa d plate. means foratomizing the metal issuing from said nozzle, said means and nozzlebeing encased within a casino: which communicates with the interior ofthe furnace and has an opening with which the atomizing orificesregister.

5. Tu means for atomizinc; metals. a cruih e having a graphite nozzleprovided with a quartz exit tube.

6. Tu means for atomizing metals, a cruible having a graphite nozzleprojecting some distance into the crucible and having signatures.

HARRY M. WILLIAMS. VICTOR W. BIHLMAN.

